This study examines the effect on learning outcomes for given topics in macroeconomics of conflating a two-semester micro and macroeconomics course into a one-semester combined micro/macro course by dropping some topics. A hypothesis that learning spillovers exist between topics is developed and tested. This is done by comparing examination results on a given set of multiple-choice questions for two large groups of students – one who had undertaken a single-semester course in macroeconomics and another who had undertaken a single-semester combined micro/macroeconomics course. In our sample, the latter group of students scored significantly less on average than the former group, after controlling for other factors, even though both had 'learned' the same topics that were examined. This suggests that positive learning spillovers do exist between topics and therefore that dropping some topics reduces the quality of learning outcomes on other topics. This has implications for the apparent trend towards reducing the mandatory number of economics units in business degrees in Australia from two to one.